1. Field of the Invention
The present invention relates to portable electronic equipment driven by a battery and a method of controlling the same.
2. Description of the Background Art
Portable electronic equipment having a protective function against impact from dropping or vibration is proposed. For example, Japanese Patent Laying-Open No. 2008-10126 discloses an image pickup apparatus with the aim of performing a proper protective function. The image pickup apparatus includes an acceleration detection sensor for detecting a level of its drop or shake. The image pickup apparatus further includes determination means for determining an output signal from the acceleration detection sensor and protection control means for stopping a recording operation of a recording medium in accordance with a determination result from the determination means. The image pickup apparatus further includes operation control means. The operation control means controls the operation of the determination means or the protection control means by setting a plurality of detection levels in the acceleration detection sensor depending on an image pickup mode or a power supply mode.
In general, portable electronic equipment is equipped with a battery as a power supply. When portable electronic equipment is dropped and subjected to impact, the battery may be moved inside the equipment to cause the battery terminal (positive electrode, negative electrode) to be momentarily detached from the connector terminal.
If the battery terminal is detached from the connector terminal even for a brief moment, instantaneous voltage drop or momentary power failure occurs. Electronic equipment is usually provided with a capacitor for preventing fluctuations of power supply voltage. However, when instantaneous voltage drop or momentary power failure occurs, electricity required for the entire operation of the equipment cannot be compensated for only with electric charge stored in the capacitor. Therefore, normal operation of portable electronic equipment may not be continued when instantaneous voltage drop or momentary power failure occurs.
In order to avoid such a problem, a sub-power supply such as an electric double layer capacitor may be provided in addition to a battery serving as a main power supply. However, a large capacity (for example, a few F) is required to make up for a drop of power supply voltage in the entire portable electronic equipment with the electric double layer capacitor. On the other hand, portable electronic equipment essentially has a limited mounting space. Therefore, there are many restrictions in mounting such a large-capacity capacitor on portable electronic equipment.
The foregoing Japanese Patent Laying-Open No. 2008-10126 discloses a technique for protecting HDD (Hard Disk Drive), which is sensitive to impact, from impact of dropping. However, Japanese Patent Laying-Open No. 2008-10126 does not show the problem of momentary detachment of the battery terminal from the connector due to impact of dropping and thus does not suggest a method for protecting electronic equipment from the instantaneous voltage drop or momentary power failure as described above.
On the other hand, in order to prevent the battery terminal from being disengaged from the connector terminal, there is a possibility of a structural solution such as a structure for fixing the battery or a structure for softening impact on the battery. However, this may lead to a complicated structure of portable electronic equipment or a cost increase.
An object of the present invention is to solve the above-noted problem and to provide a technique for protecting portable electronic equipment from instantaneous voltage drop or momentary power failure caused by impact from dropping.